Drug testing of biological specimens such as urine, saliva, sweat and hair provides an objective means of diagnosis of drug use and monitoring subjects while in treatment. Traditionally, urine testing has been used in the past, but this technology has limitations. In a series of ongoing studies, a variety of alternative biological fluids and tissues are being evaluated for their usefulness in monitoring individual patterns of substance abuse. Clinical studies were designed to determine the identity, concentration, time course, dose dependency and variability of drug and metabolite excretion in urine, plasma, saliva, sweat, skin, sebum, nails and hair following administration of single and multiple doses of drugs of abuse to human subjects. Each biological specimen appears to be unique and offers a somewhat different pattern of information regarding drug use over time. For example, hair testing offers the possibility of detecting drug use that could have occurred within a period of several months and could be useful in monitoring individuals in long-term treatment programs and in prevalence studies. In contrast, saliva testing is a short term measure of drug exposure that might correlate closely with drug levels in blood and with drug-induced effects. Sweat testing can be used for drug monitoring over a period of 1-2 weeks. Each matrix may be useful for drug testing in different settings. However, there may also be disadvantages associated with the use of a particular biological matrix. The risk of false positives arising from environmental drug contamination is being evaluated along with the possibility of ethnic bias in testing. Basic pharmacological properties such as dose-concentration and concentration-time relationships are evaluated. Overall, each biological matrix shows promise of revealing useful information regarding an individual's drug exposure history. Analysis of drugs in alternative matrices requires development of sensitive, selective and specific chemical methods for the detection and quantitation of drugs and metabolites. Analytical procedures are continually evaluated for improving the detection and quantitation of parent drug and metabolic products of cocaine, opiates, methamphetamine, cannabinoids and nicotine in blood, plasma, sweat, saliva, urine, skin, sebum, meconium and hair.